Hi All,

We're told that a retailer orders U units of an item for which he paid a total of D dollars, but he mistakenly receives (U - 3) items. We're asked for the amount he was overcharged, in terms of D and U. This question can be solved in a couple of different ways, including by TESTing VALUES.

IF... U=4 and D=8
then the original price per unit was $8/4 = $2 per unit
By receiving (4-3) = 1 item and paying $8 for it, the retailer was overcharged $8 - $2 = $6

Thus, we're looking for an answer that equals 6 when U=4 and D=8. There's only one answer that matches....

Final Answer: C

GMAT assassins aren't born, they're made,
Rich

BTGmoderatorDC wrote:A retailer orders u units of an item for which he pays d dollars. However, he mistakenly receives u - 3 items. How much was he overcharged, in terms of d and u?

A. 3d - u
B. 3du - 9
C. (3d)/u
D. (u−d)/3
E. (du)/3

Since the price per unit is d/u, the cost of u - 3 units is d/u x (u - 3) = (ud - 3d)/u, so the retailer was overcharged by:

d - (ud - 3d)/u

ud/u - (ud - 3d)/u

(ud - (ud - 3d))/u

(ud - ud + 3d)/u

(3d)/u

Answer: C

BTGmoderatorDC wrote:A retailer orders u units of an item for which he pays d dollars. However, he mistakenly receives u - 3 items. How much was he overcharged, in terms of d and u?

A. 3d - u
B. 3du - 9
C. (3d)/u
D. (u−d)/3
E. (du)/3

A retailer orders u units of an item for which he pays d dollars.
So, EACH unit costs d/u dollars

However, he mistakenly receives u - 3 items.
In other words, he received 3 fewer units than he wanted
So, he paid for 3 units that he never received (i.e., he was overcharged for 3 units)

How much was he overcharged, in terms of d and u?
He was overcharged for 3 units, and EACH unit costs d/u dollars
TOTAL overcharge = (3)(d/u)
= 3d/u

Answer: C

Cheers,
Brent